The present invention relates to a sealed push button switch.
In particular, the present invention relates to a switch in which a control rod connected to the push button is constituted by two coaxial portions, a first of which is rigidly connected to the push button and a second of which slidably engages in a support body, being slidable against the action of a spring. The said support body is provided with a plurality of fixed contacts which can be electrically connected to corresponding movable contacts disposed on the second portion of the control rod when this is moved under the thrust of the spring, to an axially extended position with respect to the support body.
The present invention further relates to a switch of the type described above in which the coupling between the control rod and the support body is protected from the infiltration of water or other external agents, and in which the said two portions of the control rod are coupled together by means of a telescopic coupling of adjustable length.
Known push button switches of the type described above are advantageously mounted, above all in motor vehicles, between a fixed member and a movable member to emit signals in dependence on the relative positions of these two members, and are able to compensate for possible assembly tolerances of the members themselves by means of an adjustment of the length of the said control rod.
This adjustment is normally made during assembly of the said two members by moving the movable member to a closure position on the fixed member, in which position the push button of the switch itself is depressed.
From the above it is clear that the said telescopic coupling must have a certain ability to slide in such a way that its length can be automatically adjusted by the movable member when closed onto the fixed member, and must, at the same time, have a certain rigidity in such a way as to retain its proper length once such adjustment has been made.
In known switches of the type described above these two contradictory requirements are not often satisfied, with the consequence that a relatively large number of switches are damaged during the adjustment step.